Dozens of firefighters killed after collapse of high rise building in Tehran

Rescue teams were searching for at least 25 trapped firefighters after a blazing high-rise building collapsed in Tehran, the city's mayor said.

State TV reported that at least 75 people, including 45 firefighters, had been hurt when the building came crashing down in a giant cloud of dust early on Thursday morning.

"About 25 firefighters are trapped inside and rescue teams are trying to get them out," Mayor Mohammad Baqer Qalibaf told state TV from the scene.

Most of the hurt had been taken to hospital and many were quickly discharged, Reuters reports with reference to the state TV.

Iranian President Hassan Rouhani had ordered "an immediate investigation" on the cause of the collapse, state news agency IRNA reported.

The building's occupants were evacuated but firefighters had still been trying to control the blaze when it came down.